The present invention relates to a stereoscopic three dimensional image projector, and more specifically, to a small three dimensional projector usable with passive glasses.
Three dimensional (3D) movies and pictures have become a popular form of entertainment due to the increased realism of the images. 3D images utilize the human physical trait of binocular vision. Human eyes are spaced about 2 inches (5 centimeters) apart, therefore each eye sees the world from a slightly different perspective. The brain receives both images and has a binocular vision function that correlates the difference between what each eye sees to determine distance. The determination of the distance provides the three-dimensional effect that a person sees.
To create a binocular image on a two dimensional surface, such as a movie or television screen, the user typically wears glasses. The glasses alter the way that the user views the images to create the simulated 3D effect. Typically there are two types of glasses, passive glasses and active glasses. The type of glasses used will depend on the type of image projection system being used.
Passive glasses rely upon an optical effect created by using different lenses for each eye. The projection system emits a sequential series of images where subsequent images are slightly offset. The images are arranged such that the user sees the first image through a first lens of the glasses (e.g. the right eye) and the second image is seen with the other lens (e.g. the left eye). Since the images are projected quickly, the user does not notice the multiple images, but rather sees a three dimensional effect. Originally, passive glasses used different color lenses to filter out images, however this limited the use of 3D images when full color images are desired. To alleviate this issue, polarized lenses were developed where each lens of the glasses allowed the transmission of different polarized light. The polarized passive lenses allowed for full color 3D images to be transmitted. Passive lenses are more common with projector type systems, such as movie theaters for example, where multiple projectors may be used to project the image.
The development of 3D television systems created a new challenge as there typically isn't enough room for multiple projectors. To accommodate this, active lenses were created. With an active lens, the glasses wirelessly communicate with the projector to synchronize the glasses operation with the images being displayed. With active glasses, the lenses are typically liquid crystal displays that can switch between transmitting light and blocking light. In this way, the glasses may rapidly switch the left and right lenses between clear and opaque. While the glasses are switching, the television is projecting a series of sequential images. When this switching is synchronized between the television and the glasses, the user experiences a three dimensional effect.